Hi all. I'm getting a rattle that I'm pretty certain is coming from the serpentine belt tensioner and/or pulley.

When I "google shopped" it I found that I can buy the pulley by itself for about $25 or the pulley and tensioner for about $40 -- not much difference.

Has anyone ever had, or heard of, a failed tensioner? Or is it usually just the pulley itself that is the problem?

The cost is one consideration but the other is the complexity of the replacement. Is it simpler to replace the just the pulley than the tensioner?

Thanks in advance,

 

Here's the long and the short of your question ....

The pulley has a bearing, but without pulling it off, you can't hardly tell whether the rattle is because the bearing surfaces have failed, or if the shaft that supports the pulley has worn down.

The tensioner is actually a spring-loaded arm that tries to maintain a consistent force on the serpentine belt, so it tracks properly, and has enough "grab" to turn the various pulleys. As the part ages, so does the spring.

Bottom line - if it were me, I'd opt for the complete replacement package

 

Thanks Mike. You explanation is helpful and your recommendation a good one.

Just one more follow-up on this...

If it were the timing chain tensioner instead that was the problem, what sound would I be hearing and when?

 

You have two pulleys, one on the tensioner and another idler pulley. I think what you may be seeing as just a replacement pulley is actually the idler pulley and not a replacement pulley for the tensioner.

I just replaced my water pump a few months ago and while I was at it, I checked my pulleys and found that the tensioner was just fine but the idler pulley had a lot of wobble in it so I replaced it. BTW, the car had 246k miles on it at the time.

If you suspect a loose pulley, just loosen the belt and check the pulleys for wobble. I'd recommend dropping in at your local Harbor Freight and get a set of the long handle wrenches or go to any hardware store and get a "tappet wrench". Can't say when the last time I saw one of these for sale but they used to be very common, a long open end wrench 1/2"x9/16" ends. Its very thin as well, handy to have for uses other than tappets too.

 

The tensioner on my Saturn failed, lost tension, on my Fiero failed lost tension and on my Mitsubishi failed. It threw it out on the freeway at 70 mph. I saw it bounce on the road and lost my power steering.

 

Thanks for the responses. I'm gonna have my son's car this coming weekend and we'll probably replace the belt, tensioner and pulleys then. I have one more question though...

I'm heading out sometime today or tomorrow to pick one up. Is that really the size I need to get? Everything else has been a metric size.

Thanks in advance.

 

Size, what are you referring to? If its the wrench, 9/16" is an almost perfect match to a 14 mm. For all practical purposes, they are interchangeable.

9/16" = 0.5625"

14 mm = 0.5512"

Barely over 1/100" difference. I have never seen a metric tappet wrench but there might be one out there. Personally if I were going to buy something for this application, I would get the metric long handle wrench set from Harbor Freight. The wider flats are more stable in this application. The long handles really help as there isn't much room and that spring is strong.

 

If this is the first time you have replaced anything on a car with a serpentine cog belt rather than V belts you are going to be surprised at the amount of tension applied to that belt and the lack of access to get at the thing to actually release the tension (or apply it what ever the case may be) Many auto supply stores will loan or rent the correct tool to replace the tensioner with. They generally want a deposit that pretty much equals the expense of buying one, the advantage being you get the deposit back when/if you return the tool.
The long handle makes a big difference in making the job easy or hard.

 

Thanks. I have replaced a couple of serpentine belts. One on a 2002 Volvo V70 XC that required me to remove the inside of the front passenger-side fender well. Even then it was a bear. As for the tension, I was mislead by how much free play I got when removing the old one. The new one had to be forced over the pulleys even with the tensioner at the full release position.

I looked at the long handled flat wrenches at Harbor Freight yesterday. They only sell multi-piece sets which I will never ever have a use for. Borrowing from the parts place is a much better idea. Thanks.